Chloridizing of ores



Sept 4L, w23, mama? J. H. HlRT CHLORIDIZING OF ORES Filed Jan. l0, 1920patented Sept. ei, i923,

sauren. sra-tres JULES HECTOR msm, or NL raso, Tnxas, AssrGNcR ToALVARADO MINING AND MILLING coNtPANY, or 'New Yoan, N. Y., a CORPORATIONor MAINE cHVLonrDIzINc or' onus.

Application iledV January 10, 1920. Serial No. 350,576.

To ,all `whom t may concern Be it known that I, JULns HECTOR HINT, acitizen of the United States, residing at El Paso, in the county of ElPaso, State of Texas, have invented certain new andA useful Improvementsin the Chloridizing of e Orcs; and I do hereby declare the following tobe a full, clear, and exact description of the invention, such' as willenable others skilled in th art to `which it appertains to make and usethe same. j

A' This invention relates to an improved process of chloridizing ores,concentrates, and other metallurgical products, to convert the metalvalues into chlorides or Oxy-chlorides which can be subsequentlyrecovered, for

example, by leaching. It is a characteristic advantage of the inventionthat the ch-loridizing operation is effected without objectionablelosses of metal values by volatilization or decomposition of thechlorides or Oxy-chlorides. Y

The' chloridizing of gold, silver, or copper ores is recognized to beadiiticult'and delicate operation because of the'losses which tend totake place, by volatilization or de composition, .if the temperature istoo high, the volatilized chlorides v'escaping and being lost or beingdecomposed into insolublemetal values which resist the subsequentleaching operation. It has accordingly been proposed to carry out thechloridizing of the ores at a temperature below the melting point ofsodium chloride, that is, at temperatures below about `800 C., and evenat temperatures far below this, inasmuch as certain of the metalchlorides have a much lower melting temperature; and it has beenproposed to eiiect the chloridizing of the ore by subjecting themixedore, usually a sul-- iide ore, and chloride, to oxidizing conditions,such as result from the introduction 1 of air or of products ofcombustion, so that the sodium chloride or other chloride would bedecomposed to form chlorine as the eiiec- `tive chloridizing agent. Suchprocesses are of limited applicability, because yof the low temperaturesrequired to prevent loss by volatilization, and the objectionable highlosses that take place if higher temperatures are employed. y

According 'to the present invention, the objections incidentto suchprior proposals are largely overcome and the chloridizing operation iseiected without objectionable loss of metal values byvolatilization ordef composition. g

I have discovered that if a body or column' of crushed ore is caused topass through a closed or sealed atmosphere of heated chloride vapors,not only can the volatili'zation losses be substantially eliminate`dbutthe temperature can be varied between rather wide limits. I have furtherdiscovered that this process can be advantageously carl ried out withnon-sulde ores, so that sulfur or suliides are not present 0r requiredto generate the chloridizing atmosphere from the chlorides.

@ne type of furnace adapted for use in the practice of the invention as4shown in the accompanying drawing in which Figure 1 is a verticalsection of the furnace; Figure 2 is a siniilars'ection inthe planetransverse to the plane in Figure l; Figure 3 is a vertical sectionthrough the 'heating iiues; and Figure 4 is a section at the line 4 4,Figure 3.

' The improved process of the present invention can be carried out indifferent ways,

and in different types ofapparatus, provided the ore body is subjectedto the chloridizing -action of the vapors of sodium chloride (or itsequivalent). The ore may thus be fed into a reaction chamber containingvaporized sodium chloride, and heated in such chamber to the necessarytempera` ture for the chloridizing reaction. I have found that aparticularly advantageous manner of carrying out the improved process isto mix the ore, crushed to a suitable size, with the proper percentageof sodium chloride or other chloride, such as calcium chloride,magnesium chloride, or 'iron chloride, and progressively feed theresulting mixture into an 'uprightpor vertical retort or chamber, and toheat the mixture therein to a suhc'ient temperature and for a sutilcienttime, to bring about the desired chloridizing of the metal values. Theupright or vertical retort or chamber 5 may advantageously be of recta/ngular cross-section and of a construction similar to that of cokeovens,but made of materials resistant to the chemical action of the materialsundergoing reaction therein, Jfor example, of firebrick. These uprightor vertical retorts or chambers may thus be made of rebriclr and withilues 6 in their side walls, with provision for example, burners 7 forheating the retorts or chambers at their central portions, or for ieee asufficient portion of their length. It is desirable not to extend theheating fines for i lthe entireheight of the retorts, or, if theVthelovver part of the retort.

flues at the upper part of the retort or cham.

ber to preheat the incoming mixture.

'When the retort or chamber has been once charged, the process becomescontinuous, and requires merelythe charging of further amounts of themixture of ore and chloride atthe top and the discharging 0f the cooledchloridized ore at the bottom through a chute 10 Wi'hich is providedwith a closure l1. The ore itself forms an effective seal for the retortor chamber, inasmuch as the cooler portions of the ore at the inlet endof the chamber effectively condenses any chloride vapors and carriesthem back into the reaction Zone. The cooled chloridized ore at thelower end of the retort or chamber similarly prevents escape of chloridevapors, although there is relatively little tendency for these vapors toescape With the ore at the bottom, inasmuch as the vaporized chloridestend rather to rise to the upper parts of the`retorts or chambers. Asthe mixture of ore and salt reaches the heated reacting zone, thevsodium chloride melts and becomes vaporized so that the reaction zone\of the retort or chamber contains a more or less saturated atmosphere ofthe vaporize'd chloride. This insures that all parts of the ore aresubjected to the action of the vapor,.

and thorough chloridizing of the metal values as they pass through thehot chloride vapors and are brought into reactive contact therewith.

In a furnace construction of the character above described, thatis, avertical or upright retort or chamber, or a series of such retorts orchambers, heated by conductionl through fines in the side Walls thereof,the

charge passing through the furnace is subjected to preheating as'itenters the upper parts of the retorts or chambers. andthe preheatedcharge is then subjected to the reaction zone, the reaction beingpromoted by the preheating of the charge. After the reaction, thechloridized ore then passes down through the cooling zone where itserves to preheat the air for combustion. The heating of such furnacescan be effected with oil or gas as the fuel in a manner which Will bereadily understood. In such. a furnace, as above pointed out, the colddescending ore entering the retorts or chambers forms an effective sealpreventing any tendency of the hot chloride vapors to escape through thetop of the retorts or chambers. The chlorides are thus kept Within theretorts or chambers untilthey have exerted their desired chloridizingaction, andY the products v of this. chloridizing action then escapefrom the bottom of the furnace. If a considerable excess of sodiumchloride is used, this .excess may pass away vith the chlorized ore,but, inasmuch as the tendency is for the hot chloride vapors to rise andnot to descend With the hottest ore as it travels through the lZone ofhighest temperature, objectionable escape of the chloride in' vapor'form iseffectively. pre-vented, proi vvided the chloridized ore ispermitted to cool sufficiently before it is discharged 'fromthe furnace.i

' The process of the present invention, as above pointedlout, is ofparticular value for the treatment of non-sulfide or'oxidized ore, asdistinguished from sulfide ores; although it is also applicable to thetreatment of sul-- fide ores. Even low grade ores, that is, orescontaining but a small percentage of metal values, can be effectivelychloridized, and the values converted into chlorides or oXy-' chloridesWell adapted for the subsequent recovery thereof by leaching. Orescontainingy as high as 10% of copper have been effectively chloridizedin this Way. Ores rela-4' 'tively rich in gold and silver have likewisebeen eectively chloridized, and the gold and silver subsequentlyrecovered from the chloridized ores.

The amount of the common salt (sodium chloride) or other chloride, suchas calcium or magnesium chlorides or iron chloride, Will vary somewhatWith variations in the values contained in the ores. to be treated.lVith gold and silver ores, it is of advantage to use only a relativelysmall amount of common salt or other chloride, for example, one'per centor less, and ores treated With such amounts of chloride are particularlyWell adapted for subsequent leaching by the cyanide process. In general,only a feu7 per cent at most of theY chloride will be required.

Any excess isv unobjectionable if the values are to be subsequentlyleached with a chloride solvent, inasmuch as the excess chloride Yusedwill assist in the subsequent leaching operation and will be therebyrecovered. The chloride can be mixed with the ore in any suitablemanner. vThe intimacy of intermixture can be promoted by using asolution of the chloride, but this will not usually be necessary becausethe chloride, even if added in a solid form, will be subsequentlyvaporized and will mainly react in its vapor state, so that'thoroughchloridizing will be effected.

Among the characteristic advantages of CII ' sen fine state ofsubdivision. ,The sodiumv chloride or other ,chloride similarly does notrequire fine grinding or thorough mixing, but the required intimacy ofintermixture and reaction is insured by the fact that-the chloride isvaporized and is present in the reacting Zone,` in part at least, in.

vapor. form. `Furthermore, a minimum amount of the sodium chloride orother chloride is` required, although any excess. not consumed, willpass through unchanged and may berecovered in they subsequentleachingoperation. Even extremely high temperatures may not beobjectionable, in-v asmuch asescape of the volatile chlorides isprevented, but such temperatures may even be advantageous infacilitating the reac-A tion and shortening the time required. Thetemperature regulation thus becomes of less importance, although thetemperature should, of course, be suhcient to insure rapid and effectivechloridizing. No sulfur or suliides are required in the ore to generatethe chloridizing atmosphere; and, if sulfides arepresent, the ore is notsubjected to atmospheric oxidation, but Athe reactionis` brought aboutbythe vaporization of the sodium chloride or other chloride Which reactsin its vaporized condition with the metal values, although reaction maylike-v Wise take place to a reater or less extent directly with the moten sodium chloride, to the extent lthat it is present unvaporized vinthe reaction zone. InasmuchV as there is no iiow of gases into and outof the reaction zone, there is no loss of volatile chlorides duettoconvection therewith.

The ore employed need not be previously dried, but may be used in amoist state, inasmuch as any moisture which it contains Will be readilyremoved in the upper preheating zonekof the furnace.

Instead of carrying out thef process in furnaces of the constructionabove referred to, other suitable types of furnaces can be used whichwill enable the desired heating and reaction to be brought about.Horizontal or inclined heated chambers or retorts can thus be used,provided they are provided With suitable heating means for heating themto the proper temperature and with means for supplying thereto the oreland chlorideand for removing therefrom the chloridized ore. Thetemperature required for the process can, as above pointed out, bevaried rather widely, inasmuch as considerably'increased temperaturesWill not cause objectionable loss ofthe volatile chlorides, orobjectionablev decomposition thereof.; When common salt (sodium.chloride) is used, Which-has a melting point of about 804, thetemperature lshould preferably be maintained around 800 'to 900 orsomewhat higher.

With calcium or magnesium chlorides, Which have a somewhatk lowermelting point,

somewhat lower temperatures can be used.

The cold chloridized' ore can be subseuently treated in any suitablemanner for t e recovery of the values therefrom. lThese values, intheform of chlorides or oxychlorides, are Well adapted for recovery byleaching operations, forexample, by leachprises subjecting a body of orefed at a ratev which ensures the presence of a layer' ofy cooler oreoverlying the reaction zone, tothe chloridizing action of an atmospherecontaining the vapors of a suitable volatileV chloride While protectingthe same from atmospheric oxidation and preventing escape ofvolatilemetal chlorides by condensing the latter in the overlyin layerfof coolerl ore.

A2. The method ofc loridizing ores, metal- I lurgical products and .thelikey which comprises mixing the ore with a suitable chloi ride, feedingthe mixture at a ratewhich ensures the presence ofa cooler layeroverlying the reaction zone, heating the mixture While protected fromatmospheric oxidation to a suiiicient temperature to cause reactionbetween the chloride and the metal ivalues of the ore, and preventingescape of the volatile metal chlorides by condensing the latter 1n theoverlying coolerlayer.

I 3. The method of chloridizingores, metali lurgical products 4and thelike, vv'vhich com-v prises mixing the ore with a suitable chloride,confining the mixture as a compact column in a suitable receptacle andheating the column intermediate its ends Whilev protected from contact'with the products of combustion to a sufficient temperature to efi fectthe desired chloridization.L

4. The method of chloridizing'ores, metallurgical products and the like,which comprisesprogressively feeding a charge of ore admixed with asuitable chloride through a reaction zone at a rate which ensures thepresence of a cooler layer overlying the reles action zone, heating themixture to a sufficiently high temperature to effect the de-1 sii-edchloridization and preventing escape of,the volatile chdorides from thecharge by condensing the latter in the overlying cooler' layer.

5. The method of chloridizing ores, metallurgical products and thelike,-which 'com- `prises progreively-feeding a charge of ore admiXedwith a suitable chlorideinte a preheating ione and then into ka reactingzone,

heating the same in the reacting -zone to the reactingtemperature whileprotected from' atmospheric oxidation, yand subsequently passing thechloridized ore through a suitable cooling zone, the preheating andcooling zones being arranged to prevent escape y of volatile chlorides.through the material contained therein. f

6. The methodof chloridizing ores, metallurgical products and the like,which com- -p'rises establishing a body of such-,material admixed With achloridizing agent and subjecting the body to heat lfrom an externalsouro'e at a zone intermediate its ends While the `ends are maintainedin a cooler state.

ends are maintained in a cooler state'and' advancing the body throughsaid zone bythe Withdrawal of chloridized material at one end and theaddition of fresh material at the other.

In testimony whereof I affix my signature.

JULES HECTOR Hier.

